{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T13:41:05Z","timestamp":1769521265027,"version":"3.49.0"},"reference-count":40,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,2,14]],"date-time":"2023-02-14T00:00:00Z","timestamp":1676332800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Information","award":["U20A20172"],"award-info":[{"award-number":["U20A20172"]}]},{"name":"NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Information","award":["U1909212"],"award-info":[{"award-number":["U1909212"]}]},{"name":"NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Information","award":["2021C05004"],"award-info":[{"award-number":["2021C05004"]}]},{"name":"NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Information","award":["2023C01192"],"award-info":[{"award-number":["2023C01192"]}]},{"name":"NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Information","award":["2022C03G1364207"],"award-info":[{"award-number":["2022C03G1364207"]}]},{"name":"NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Information","award":["2021YFB3602200"],"award-info":[{"award-number":["2021YFB3602200"]}]},{"name":"Zhejiang Province Key R &amp; D programs","award":["U20A20172"],"award-info":[{"award-number":["U20A20172"]}]},{"name":"Zhejiang Province Key R &amp; D programs","award":["U1909212"],"award-info":[{"award-number":["U1909212"]}]},{"name":"Zhejiang Province Key R &amp; D programs","award":["2021C05004"],"award-info":[{"award-number":["2021C05004"]}]},{"name":"Zhejiang Province Key R &amp; D programs","award":["2023C01192"],"award-info":[{"award-number":["2023C01192"]}]},{"name":"Zhejiang Province Key R &amp; D programs","award":["2022C03G1364207"],"award-info":[{"award-number":["2022C03G1364207"]}]},{"name":"Zhejiang Province Key R &amp; D programs","award":["2021YFB3602200"],"award-info":[{"award-number":["2021YFB3602200"]}]},{"name":"National Key R&amp;D Program of China","award":["U20A20172"],"award-info":[{"award-number":["U20A20172"]}]},{"name":"National Key R&amp;D Program of China","award":["U1909212"],"award-info":[{"award-number":["U1909212"]}]},{"name":"National Key R&amp;D Program of China","award":["2021C05004"],"award-info":[{"award-number":["2021C05004"]}]},{"name":"National Key R&amp;D Program of China","award":["2023C01192"],"award-info":[{"award-number":["2023C01192"]}]},{"name":"National Key R&amp;D Program of China","award":["2022C03G1364207"],"award-info":[{"award-number":["2022C03G1364207"]}]},{"name":"National Key R&amp;D Program of China","award":["2021YFB3602200"],"award-info":[{"award-number":["2021YFB3602200"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>P(VDF-TrFE) is a promising material for flexible acoustic devices owing to its good piezoelectric performance and excellent stretchability. However, the high density of internal pores and large surface roughness of the conventional P(VDF-TrFE) results in a high propagation attenuation for acoustic waves, which limits its use in flexible acoustic devices. In this paper, a novel method based on two-step annealing is proposed to effectively remove the pores inside the P(VDF-TrFE) film and reduce its surface roughness. The obtained P(VDF-TrFE) film possesses excellent characteristics, including a high breakdown strength of &gt;300 kV\/mm, a high-purity \u03b2-phase content of more than 80%, and high piezoelectric coefficients (d33) of 42 pm\/V. Based on the low-porosity \u03b2-phase P(VDF-TrFE) film, we fabricated flexible film bulk acoustic resonators (FBARs) which exhibit high sharp resonance peaks. The pressure sensor was made by sandwiching the FBARs with two PDMS microneedle patches. Heartbeat and respiration rate monitoring were achieved using the pressure sensor. This work demonstrates the feasibility of high-performance flexible piezoelectric acoustic resonators based on low-porosity P(VDF-TrFE) films, which could see wider applications in the wearable sensors for both physical and chemical sensing.<\/jats:p>","DOI":"10.3390\/s23042136","type":"journal-article","created":{"date-parts":[[2023,2,15]],"date-time":"2023-02-15T02:01:10Z","timestamp":1676426470000},"page":"2136","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Flexible Film Bulk Acoustic Resonator Based on Low-Porosity \u03b2-Phase P(VDF-TrFE) Film for Human Vital Signs Monitoring"],"prefix":"10.3390","volume":"23","author":[{"given":"Zhentao","family":"Yu","sequence":"first","affiliation":[{"name":"Key Laboratory of Advanced Micro\/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"}]},{"given":"Feng","family":"Gao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Advanced Micro\/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"},{"name":"ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, China"}]},{"given":"Xiangyu","family":"He","sequence":"additional","affiliation":[{"name":"Key Laboratory of Advanced Micro\/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9798-5149","authenticated-orcid":false,"given":"Hao","family":"Jin","sequence":"additional","affiliation":[{"name":"Key Laboratory of Advanced Micro\/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"},{"name":"ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8715-7072","authenticated-orcid":false,"given":"Shurong","family":"Dong","sequence":"additional","affiliation":[{"name":"Key Laboratory of Advanced Micro\/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"},{"name":"ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, China"}]},{"given":"Zhen","family":"Cao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Advanced Micro\/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0310-2443","authenticated-orcid":false,"given":"Jikui","family":"Luo","sequence":"additional","affiliation":[{"name":"Key Laboratory of Advanced Micro\/Nano Electronic Devices and Smart Systems of Zhejiang, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China"},{"name":"ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,14]]},"reference":[{"key":"ref_1","first-page":"31","article-title":"Flexible Hybrid Sensors for Health Monitoring: Materials and Mechanisms to Render Wearability","volume":"32","author":"Gao","year":"2020","journal-title":"Adv. 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